442 



11d 4d 



OTTO F. KAMPMEIER 



25 13 



11s 



17 21 4.5 



Fig. 16 Transverse section taken a few sections beyond the one represented by 

 the preceding figure from a 23 mm. pig embryo (series 23a, J.H.E.C., slide 26, 

 section 12), X 200. 4d, long fusiform space in the right thoracic duct line, and 

 mesenchymal bridges traversing its lumen; 4s, lymphatic space at the level of the 

 left Cuvierian duct {21) and in the pathway of the left thoracic duct; lid, lis, 

 right and left postcardinals; 13, aorta; 17, eosophagus; 25, branch of the post- 

 cardinals. (Reconstruction, fig. 30.) 



exhibits the same peculiarities of character. This again is fol- 

 lowed by tissue which is still undifferentiated but coarsely retic- 

 ulate and persistently suggests the potentiality of further lympha- 

 tic anlagen. Both of the spaces described and figured are situated 

 in the axis of the injected channel and consequently in the axis 

 of the ultimately complete thoracic duct. 



On the left side in series 23a the principle of lymphatic develop- 

 ment is the same and is expressed fully as well as on the right 

 side. The injected segment of the left thoracic duct limb (5s, 

 figs. 30 and 13) is much shorter than that of the right, but it is 

 slender and often it can only be traced by a 'mossy' path due to 



